1 วิชาสัมมนา MI การออปติไมซ์วิธีหาเส้นทางแบบไบ ไดเรคชั่นแนลใน โมไบล์ไอพีบนเครือข่ายแลนไร้สาย Bi-directional Route Optimization in Mobile IP over Wireless LAN W. Chun-Hsin นายวโรดม วีระพันธ์ อาจารย์ผู้ควบคุมวิทยานิพนธ์ผศ. อภิเนตร อูนากูล หลักสูตร วศ. ม. สาขาวิชาวิศวกรรม คอมพิวเตอร์ คณะวิศวกรรมศาสตร์ สถาบันเทคโนโลยีพระจอมเกล้าเจ้าคุณ ทหารลาดกระบัง

2 วัตถุประสงค์ 1. พัฒนาโครงสร้างการสื่อสารข้อมูลแบบ โมไบล์ให้มีประสิทธิภาพสูงสุด 2. ประยุกต์ใช้กับระบบสำรวจข้อมูลที่ชาญ ฉลาด เพื่อพัฒนาระบบนำทางสำรวจ ท้องถิ่น

3 Outline n Introduction –Motivation and Goal –Mobile IP Overview –Issue with Base Mobile IPv4 –Route Optimization and Reverse Tunneling n Proposed Bi-directional Route Optimization –Correspondent Agent –Subnet-based Direct Tunneling –Binding Optimization n Implementation n Conclusion

4 Motivation and Goal n To developed a mobile communication infrastructure that supports cost- effective wireless broadband access for Intelligent Transportation Systems. n Have developed a regional guidance system at Academia Sinica as a testbed. – MobileIPv4 – Outdoor Wireless LAN (802.11b) –GPS

5 Mobile IP Overview n What is Mobile IP? n How Mobile IP work? n Movement detection n Registration scenario n Triangle routing

6 What is Mobile IP? n Question? –What is Mobile IP? –Is it need to be a mobile phone? n Answer: –Internet Protocol enhancements that allow transparent routing of IP datagrams to mobile nodes in the Internet. [RFC 3220, Jan 2002] –IP address that can mobile (movement). It can apply with every mobile terminal devices. Not need to be only mobile phone. [My opinion]

7 How Mobile IP work? n Please imagine, you always work at home. n If you need to work outside home (another home) for someday. n If someone need to contact you. Then, he sends the urgent regular mail to you. n Question? –If you need to receive your mail. How you manage your address?

8 How Mobile IP work? n Solution: –When you need to go another home. You need to send mails to every your friends. n Impacts: –You need to send mails every times that you go outside. –How you sure that all of your friends will get your mail. –When you go outside home, some friend don’t need to contact you.

9 How Mobile IP work? n Better Solution: When you go outside home. You just tell postman to forward your mail to new location.

10 How Mobile IP work? n How it relate with Mobile IP? n Solution: –Just change these words following table below:

11 Mobile IP scenario

12 Move detection n There are 2 ways to detect movement. –Check from ICMP packet’s lifetime. Agent broadcast ICMP router advertisement. To update registration lifetime field in mobile node from that agent. –Compare network prefix from routing advertisement. Network prefix

13 Stateless and stateful configuration n stateless address autoconfiguration –Configuration IP address automatically by using new features in IPv6. n Stateful address autoconfiguration –Configuration IP address automatically by using Dynamic Host Control Protocol (DHCP) Server.

14 Registration Scenario

15 (de-) Registration Scenario

16 Mobile Networks for a Regional Guidance System n Requirement –Visitors’ mobile nodes can request contents from ordinary Internet servers or local specific servers as usual. –Local servers can deliver contents to both visiting mobile nodes and ordinary Internet users.

17 Mobile Networks for a Regional Guidance System (Cont.) n Observations Client-server applications: –A session is usually initiated by the client. –The client usually requests contents from multiple servers of the same provider. eg. {www, gif, search}.yahoo.com

18 In a guidance system: n Guidance system –Home Agents (HAs) are outside and Correspond Nodes (CNs) are inside the mobile Intranet. –Neighboring Mobile Nodes(MNs) of the same FA access similar location-based contents from the same or surrounding correspondent nodes. n Goal –Reduce access latency for MNs. –Reduce overhead for border router.

19 Issue with Base MobileIPv4 (RFC2002/3220/3344) All packets sent to MN are intercepted by its Home Agent and then tunneled to MN. n Triangle Routing Problem –Long delay for MN –Overheads for border router and HA n Ingress Filtering Problem –Packets from MN can’t be directly sent to CN. Topologically incorrect packet are dropped by the routers. (RFC2267)

20 Route Optimization and Reverse Tunneling n Route Optimization –An Internet Draft solving unidirectional triangle routing problem (Johnson & Perkins), but requiring all CNs to maintain Binding Cache for each MN. n Reverse Tunneling –RFC2344 solving ingress filtering problem, but creating “reverse triangle routing problem”

21 Proposed Bi-directional Route Optimization n Route Optimization –transparency issue in CN => Packet Tunneling and de- tunneling are performed by Correspondent Agent. => Binding Cache n Reverse Tunneling –reverse triangle routing problem => Packet from MN can be Directly Tunneled from FA to CA/CN. => Tunneling Cache

22 Proposed Bi-directional Route Optimization (Cont.) n Enhancements +Correspondent Agent Binding Cache +Direct Tunneling Tunneling Cache +Subnet-based Route Optimization +Binding Optimization

23 Subnet-Based Route Optimization

24 Binding Optimization for Fast Handoff n In addition to HA, FA can also send Binding Update message directly to particular CAs. –Reduce the handoff delay to update the binding to MN without going through HA. n Support backward compatibility with the base mobile IP.

b WLAN Infrastructure at Academia Sinica

26 Implementation: AutoPC Prototype

27 Navigation Services

28 Audio and Video Streaming

29 Conclusion n Bi-directional route optimization is proposed to improve the routing efficiency of mobileIPv4 in a regional guidance system over wireless LAN. –Correspondent agent –Direct tunneling –Subnet-based route optimization –Binding optimization n The proposed approach can reduce the access latency of mobile nodes and the overhead of the border router significantly. –Reduce the length of a routing path. –Reduce the traffic at the border router.